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the 6 month rule? How accurate is a PCR?

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hello doctor,
can the amount of hiv virus that enters the body at the time of infection have any bearing on the length of the "window period?" What if a very little amount entered the body by "pre-cum" and it stayed dorment for a long period of time? is tis possible? it is said that an antibody test at six months is over 99% conclusive. does this mean its 99% certain that it will detect antibodies if they are present or does it mean that at 6 months its 99% certain that antibodies will be present? I'm very anxious even after 6 1/2 month NEG test and 8 month NEG test. i have read forums where people say that they test NEG at 6 months but at a year test POS. One person even stated that she tested NEG up to 11 months but still having symptoms and her doctor ordered another HIV test. What about the 6 month rule? How accurate is a PCR? sorry, i know i have alot of questions

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replied May 8th, 2011
HIV and AIDS Answer A22728
Hello and welcome to E health forum.

Though a few virions can become dormant, it is highly unlikely that all the virions will become dormant. Even if a few virions initiate the disease process, they will be detected by the body's immune system and antibodies will be produced to them, and will be detected in the serum.

If you had an infective exposure, then there is a 90% chance that you develop the antibodies to HIV within 12 weeks of exposure.

The infective dose will not affect the test results in any way.

Please understand that tests for HIV (ELISA) detect the presence of antibodies to HIV, which usually present within 4 - 12 weeks of exposure, depending on the severity of exposure (Probable no of virions that might have entered the blood stream).

Hence once antibodies are synthesized by the body, they remain in considerable amounts as long as viremia is present.

Hence the chances of very sensitive tests (like ELISA) giving a negative result, in presence of antibodies to HIV, is very negligible.

if antibodies are present - the test is positive, if they are absent - the test is negative. It is as simple as that.

There is no reason to doubt test results if they are done at the correct interval.

In your case, since the tests results at 8 months have been negative, it is certain that you do not have HIV infection.

I hope this helps.

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